Medium sized pumps are normally used for spitters or fountains
The head will usually be from 300 gph to 660 gph, with the larger one used to get the water higher or stronger. Be careful with spitters and fountains because if the water shoots too far in the air, it can splash out of the pond and soon you have pumped your pond dry.
For medium sized pumps, I like the Little Giant 350 gph
Just be sure to keep the impeller clean on smaller pumps for longer life. They usually need to be cleaned once a month if you feed your fish.